Answer: People are not able to scuba dive in deepest parts of the oceans because in greater depths temperature decreases and pressure increases,as per temperature-pressure relation.
What is the temperature -pressure relation with depth?
Temperature and pressure increase with an increase closeness towards the earth's crust .The temperature increases as it is hot towards earth's core and pressure increases along with depth as there is less pressure of air acting on the body.Pressure increases with temperature because as temperature increases kinetic energy of particles increases and thus pressure increases.
In case of pressure and temperature of ocean or water bodies, the temperature of water decreases as depth increases as sunlight is unable to reach deeper layers of water and pressure increases with depth because the air pressure which is acting on a body increases with depth.
Step-by-step explanation: